SpaceWar with Godot

This project is a usage sample of rollback netcode using Backdash in Godot.

It shows a basic example of an online lobby for NAT traversal using UDP hole punching.

Video

How does it work?

This enables a P2P connection over the internet, this is possible using a middle server which all clients know. The server catches the IP address and port of a client and sends it to the others.

The current server runs almost as a simple HTTP with JSON responses. It keeps the lobby info with sliding expiration cache.

When a client enters the lobby the server responds with a token of type Guid/UUID. It is used a very basic Authentication mechanism.

The client uses HTTP pooling to get updated information on each lobby member/peer.

When logged in, every client needs to send a UDP package with their token to the server. The server uses the package header metadata
to keep track of their IP and open Port.

⚠️ UDP Hole punching usually does not work with clients behind the same NAT. To mitigate this the server also tracks the local IP and port on each client to check if the peer is on the same network.

Controls

• Arrows: Move
• Space: Fire
• Left Ctrl: Missile

Running

Server

Note

This project uses an already published demo lobby server.

The server URL is configured in the settings.ini file and you can start your own server from here:

After cloning the repository run this command on the server project directory:

dotnet run .

• Default HTTP: 9999
• Default UDP : 8888

Tip

💡 Check the swagger API docs at http://localhost:9999/swagger